1. Field
The disclosure is directed to a method for preparing nanocrystals coated with metal-surfactant layers. More specifically, the method is directed to the preparation of nanocrystals with minimal surface defects, high luminescence efficiency and good stability.
2. Description of the Related Art
A semiconductor nanocrystal, also called a “quantum dot,” is a crystalline semiconductor material of the size of a few nanometers and consists of several hundred to several thousand atoms. A semiconductor nanocrystal has a large surface area per unit volume and exhibits a variety of effects (e.g., quantum confinement) that are different from those exhibited by a bulk material having the same composition. These effects are due to its small size. These structural characteristics and effects account for unique physicochemical properties of the semiconductor nanocrystal different from those inherent to the constituent semiconductor materials. Particularly, the photoelectronic properties of nanocrystals can be controlled by varying the size of the nanocrystals. Research efforts are directed toward the development of nanocrystals applicable to a variety of display devices, including bioluminescent display devices.
However, since the surfaces of semiconductor nanocrystals are prone to oxidation, surface defects are likely to be caused. As a result, the luminescence efficiency of the semiconductor nanocrystals is liable to deteriorate and the core-shell structure of the semiconductor nanocrystals is destroyed.
In attempts to solve such problems, etchants have been used to remove surface defects of nanocrystals. However, etchants (e.g., HF) remove large amounts of organic materials present on the surfaces of nanocrystals rather than defects, making the nanocrystals unstable.